Abstract: We point out that results obtained by M. Ribaric and L. Sustersic,hep-th-0403084, and by M. Blasone, P. Jizba and H. Kleinert, quant-ph-0409021,suggest that the path-integral formalism is the key to a derivation of quantumphysics from classical, deterministic physics in the four-dimensionalspace-time. These results and the -t Hooft conjecture, hep-th-0104219, suggestto consider a relativistic, non-material medium, an ether, as a base fornon-local hidden-variable models of the physical universe.